Recent long weekend round trip to the cabin ~400km netted an impressive (IMHO) 6.0L/100km. Cruise set at 107km/h but adaptive cruise was working overtime with heavy long weekend traffic.
On a calm day, the Corolla gets about 6.0L/100km at 100 km/h.
At almost 12,000 kms the lifetime average for the Civic is 6.1L/100km, but that's basically two summers and one winter. For our CR-V it's sitting at a lifetime average of 7.9L/100kms and 16,000kms, but that has a lot more highway miles than my Civic, a few trips to Ottawa and a trip to northern NL brought it down to that level, otherwise it'd be in the low 8's. Overall, I'm pretty happy with both for fuel economy.
What is funny is the trip computer and how it changes significantly when the low fuel light comes on. Last weekend I had to mow the lawn at a family property outside of the city. Total distance is around 75kms, vehicle stated range was 98kms. I wanted to get this little trip done before fueling up at Costco on the way home. The gas light comes on around 60kms, the next 30kms fall off at an accelerated rate. So each km I drove it feel more than 2kms in stated range. I got to the property with around 45kms of range stated, which is still plenty as it is only about 35kms to get to Costco on the way back. I passed a sign going back to the city saying 31kms to Fredericton, I think the range stated was 35kms. Once I hit 30kms of range it reverts back to a more true calculation. I got to Costco with 15kms of range stated, put 47L in, and the tank is 53L in size, so technically I had closer to 100kms of range left. Of course this was all done without my wife as she would have freaked out. I made sure to take my little jerry can of gas for the mower with me, but it only had maybe 2L left in it, but that would have given me 10+kms of extra range.
I have never ran out of gas in my life, and I'd say it's less likely with modern vehicles as they use scare tactics like this to force you into getting gas well in advance.